Vol. 11, Special Issue 4 (2022)

Author(s):
Chandrakar Harshana, Pradhan Mukesh and Sahu Khilesh Kumar

Abstract:
Evapotranspiration (ET) is one of the important parameter in hydrology and development of watershed. Concept of ET is crucial mainly in water requirements to crops and planning of any water resources structures. ET is the combined processes of evaporation from soil and plant surfaces and transpiration from plant tissues. Recently, the Food and Agricultural Organisation has suggested FAO-56 PM method (modified PM method) as a standard method for calculating reference evapotranspiration (ET0), because this method is applicable to all types of season and different climates and gives more accurate result when compared with the physical methods like Lysimeter and Class A Pan. Here nine different estimated PET methods are considered for present study, which are Modified Penman, Hargreaves, Turc, Blaney-criddle, Christiansen, Pet open Pan, Penman Monteith, Thornthwaite and Measured PET are the methods. Chhattisgarh plain agro climatic zone is selected for this research work from the period of 1993 to 2016. The objective of this study is to estimate the PET by different empirical equations on weekly, monthly, seasonal as well as annual basis. It is clear from this study that weekly and monthly PET value of Raipur station showed that the values obtained were lower during winter (Dec-Jan) and higher in summer (April-may). During the period (1993-2016) maximum annually average total PET was found for the Thornthwaite method (1958.8 mm). The minimum annually average total PET was found for Open pan method (1278.6 mm). The seasonal PET values were found minimum during winter followed by post-monsoon, monsoon and ultimately followed by pre-monsoon. Among all the methods Turc (459.5 mm), Hargreaves (575.8 mm) and Measured PET (550.3 mm) recorded the maximum value in the season of monsoon and rest were all methods recorded the maximum value in the pre monsoon season.